Have you ever been working on your pc and realized that someone is spying on you? Well this could be a simple solution to your problem. A rear mirror for your desktop is a simple, but functional solution.
Here is what you need:
1.) One Sugru pack (you choose your favorite color)
2.) One small mirror
The procedure is simple. Open one Sugru pack with your favorite color, and make two pieces out of it as you see in photos.
Attach them to the small mirror which you've got and then attach the other ends of sugru to the pc monitor. Sit comfortably in your chair and adjust it. Take your time, it is the most important step after all.
Good luck and have fun :D